Materials Literature
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The phase transitions in two liquid crystalline polyesters have been studied by diffraction techniques employing synchrotron radiation. The two polyesters, derived from p,p ‘ -bibenzoic acid and 3-methyl-1,6-hexanediol, only differ on the optical activity of the chiral spacer: both the active and racemic polymers have…
The response of organic polymers and proteins including poly(methyl methacrylate) (PMMA) and the protein bovine serum albumin (BSA) to a short duration 4.5 GPa shock pulse, termed a “nanoshock”, is studied using ultrafast coherent Raman spectroscopy (CARS) to monitor density-dependent vibrational frequency shifts of a…
The tetra(4-methoxyphenyl)phosphonium iodide C 28 H 28 O 4 PI (MOPPI) is a crystal built up with quasi octupolar tetrahedral chromophores having quadratic nonlinear optical (NLO) properties. The calculated values of the highest tensor component β xyz for the hyperpolarizable chromophore, in its most stable S 4 geometr…
Second- and third-generation alkoxysilyl-terminated carbosilane dendrimers have been used as building blocks for the synthesis of high surface area xerogels, which were characterized by 29 Si CP MAS NMR spectroscopy, nitrogen adsorption/desorption porosimetry, IR spectroscopy, transmission electron microscopy (TEM), a…
Cellulose ethers containing alkyl side chains of varying length were prepared from (2-hydroxypropyl)cellulose and alkyl bromides. Two different synthetic methods were employed. The average degree of alkyl substitution of the product polymers ranges from 1.8 to 2.8, as determined from 1 H NMR spectroscopy. Surface pres…
The competitive adsorption behavior between oxygen- and nitrogen-containing functionality in poly(methyl methacrylate- co -2-vinylpyridine) (MMA2VP) and poly(methyl methacrylate- co -4-vinylpyridine) (MMA4VP) random copolymers onto alumina substrate was investigated. The adhesive strength of both the MMA2VP/alumina an…
The rupture of standing three-dimensional soap foams was examined. A foam of controlled size and water content was produced in a vertical column and the evolution of its liquid fraction under gravitational drainage was followed by electrical conductivity measurements. Using simple models to describe simultaneously foa…
A new regioregular polythiophene derivative bearing side chains with exactly six oxyethylene units has been synthesized. From the thermochromic and ionochromic behavior of this polymer, it is concluded that the hexa(oxyethylene) side chains induce a more planar conformation of the polythiophene backbone than random-le…
The chlorination and regeneration of poly(3-(4-fluorophenyl)thiophene) (PFPT) thin films has been investigated using cyclic voltammetry, energy dispersive analysis by X-ray, and X-ray photoelectron spectroscopy. A complete substitution of all 4-thiophene positions of the electrodeposited polymer is achieved by electro…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPorphyrin-containing [2]-Rotaxanes: Metal Coordination Enhanced Superexchange Electron Transfer between Noncovalently Linked ChromophoresMikael Andersson, Myriam Linke, Jean-Claude Chambron, Jan Davidsson, Valérie Heitz, Jean-Pierre Sauvage, and Leif HammarströmView Au…
In the course of surface defect characterization on MgO nanoparticles three different types of O - species were observed by electron paramagnetic resonance (EPR) spectroscopy. They are a result of UV excitation under high-vacuum conditions/in O 2 atmosphere or of surface color center bleaching by N 2 O, respectively.…
Transparent alumina gels have been prepared with a simple precursor system, aluminum tri- sec -butoxide−2,4-pentanedione−2-propanol−nitric acid, at optimal acacH/ASB mole ratios of 0.3−0.4. The specific surface areas ( S BET ) of the prepared gels are in the range 552−560 m 2 /g after calcination at 400 °C for 2 h. It…
Decane has been used as swelling agent to enlarge the pore size of pure silica MCM-41 materials. The synthesis conditions such as the swelling agent/surfactant molar ratio, the adding sequence of swelling agent, etc., have been studied. The role of decane and the effect of crystallization time and temperature on the s…
The potential- and coverage-dependent infrared absorption spectroscopy (IRAS) of linearly bound CO on single-phase polycrystalline arc-melted Pt, PtRu(1/1), PtRu(8/2), PtOs(8/2), PtRuOs(8/1/1), PtRuOs(65/25/10), and Ru electrodes in 0.5 M H 2 SO 4 are correlated with the potential-dependent X-ray photoelectron spectro…
We reconsider the exponents s and μ that characterize the behaviors of the viscosity and the elastic modulus near the Sol−Gel transition. This is done by studying the dynamics of the elastic chain that connects neighboring nodes. We assume that the characteristic time for the latter is the same as for the whole cluste…
We study analytically kinetics of an elementary bimolecular reaction scheme of the Langmuir-Hinshelwood type taking place on a d-dimensional catalytic substrate. We propose a general approach which takes into account explicitly the influence of spatial correlations on the time evolution of particles mean densities and…
A number of recent studies have explored the energetics of intermediate-sized clusters, such as small fullerenes. For example, the isomer energies of C 20 have proven difficult to ascertain as different theoretical methods give widely varying results. For cluster sizes around 20−30 atoms, it is not immediately clear w…
Elastin-mimetic peptide polymers have been synthesized, and the morphological properties of fabricated small diameter fibers and nonwoven fabrics have been characterized. An 81 kDa recombinant protein based upon the repeating elastomeric peptide sequence of elastin (Val-Pro-Gly-Val-Gly) 4 (Val-Pro-Gly-Lys-Gly) was obt…
We provide a wet chemical approach for organizing randomly tangled single-walled carbon nanotubes (SWCNTs) on gold surfaces. The as-grown nanotubes were first chemically cut into short pipes and thiol-derivatized at the open ends. The ordered assembly of SWCNTs was made by their spontaneous chemical adsorption to gold…
Microstructured particles were synthesized by growing colloidal crystals in aqueous droplets suspended on fluorinated oil. The droplets template highly ordered and smooth particle assemblies, which diffract light and have remarkable structural stability. The method allows control of particle size and shape from sphere…